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Delaware Bay

Site Facts

Country, State, Province/Region:

United States, Delaware and New Jersey:

80 km of shoreline along the lower Delaware Bay, between Cape May and Cape Henlopen


39 10' N; 75 20' W



Basis for Designation:

More than 500,000 shorebirds annually.


21,208 hectares (52,406 acres)


May 1986

Site Owner/Steward:

U.S. Fish and Wildlife, New Jersey and Delaware Division of Fish and Wildlife

Site Partners:


Human Population within 100 km:



Amanda Dey
Endangered and Non-Game Species Program
New Jersey Division of Fish and Wildlife


Land included in reserve is coastal, from hightide line down. Mostly narrow, sandy beaches, some mud flats; area made up of shorefront and lowtide flats, including dunes, sandy beaches and sandy/muddy mouths of rivers, adjacent tidal salt marshes, and salt water impoundments. There are extensive freshwater and saltwater wetlands throughout the Delaware River and Bay estuary. 

The extensive wetlands in the Delaware River Estuary provide excellent resting habitat and nesting sites for many species of migratory waterfowl, bald eagles, ospreys, northern harrier, waders (including yellow and black crowned night herons) and migrating raptors. The area functions as a major staging area for 80 percent of the Atlantic flyway population of Snow Geese (up to 200,000). Several federal and state endangered and threatened species are supported including: Bald Eagle, Peregrine Falcon, Piping Plover, Pied-billed Grebe, Short-eared Owl, Delmarva Fox Squirrel, and Shortnose Sturgeon. Delaware Bay is also the site of the largest spawning concentration of horseshoe crabs along the Atlantic coast. 

The northbound migration of shorebirds coincides with horseshoe crab spawning in the bay. Shorebirds have been found to feed mostly on horseshoe crab eggs on the bay beaches, but some species, such as the Semipalmated Sandpiper, Dunlin, and Short-billed Dowitcher, rely more heavily on marsh habitats (Clark and Niles). All shorebirds move between the beaches and marshes for feeding, resting and roosting. NJ Division of Fish, Game and Wildlife, in conjunction with the Delaware Department of Fish and Wildlife - Nongame and Endangered Species Program, conducts annual surveys of shorebird abundance on beaches. Total birds counted on beaches in aerial surveys over the 6-week migration period range from 250,000 to over 600,000 (May through mid-June). Birds observed in tidal marsh habitats are estimated at 700,000, approximately two times that on bay beaches. (Clark and Niles). But species that associate more with marshes than beaches, are underestimated by aerial surveys (Gelvin-Innvaer, 1990, 1991).

Four species accounted for 99% of birds observed on Delaware Bay beaches: 

Semipalmated Sandpipers 30-70%

Ruddy Turnstones 20-35 %

Red Knots 15-20 %

Sanderling 4-6 %

Dunlin and Short-billed Dowitchers account for another 2-8 % (numbers fluctuate yearly). 


In the News

Red Knot Reunions

Ecology & Conservation

Land Use: 

The coast of New Jersey and Delaware is heavily developed in parts (mostly private homes), with the Bay being less developed. There are large areas of state and federally-owned land. Many towns along the Bay are fishing villages inhabited more heavily in the summer. Human activities vary from walking, birding, fishing, and sunning, to periodic high human disturbance, including all terrain vehicles (on some beach es), commercial horseshoe crab harvesters, high concentrations of bird watchers, and dogs chasing birds. In the river and upper estuary, industrial land use includes chemical industries. The most important economic activities in the area are industry and fishing/ shell fisheries. The Delaware River and Bay are heavily used for oil transport; in fact the Bay is the largest port of transport on the East Coast of North America.Protection:

On the Delaware side of the Bay, about 50% of the coastline, 20,670 hectares (51,054 acres) of wetlands, is in state and federal ownership and thus protected. In New Jersey, approximately 21,016 hectares (51,910 acres) of wetlands associated with the Bay are in state ownership, mostly as Fish and Wildlife Management Areas (FWMA). Federal areas under protection include: Cape May National Wildlife Refuge, NJ, and Bombay Hook and Prime Hook National Wildlife Refuges, Delaware. New Jersey Wildlife Management Areas include: Mad Horse Creek, Dix, Egg Island, Fortescue, Nantuxent, Heislerville, Dennis Creek, and Higbee Beach. Delaware Wildlife Management Areas include: Woodland Beach, Little Creek, Ted Harvey, Prime Hook and Cape Henlopen. The Nature Conservancy has launched a 3-yr, 15 million dollar fund-raising campaign to acquire 13,500 square miles along the Delaware River Basin and additional areas are protected by The Natural Lands Trust, NJ Natural Lands Trust, and the Cape May County Park Commission. 

In Delaware, a comprehensive management plan for tidal wetlands (including recommendations for shorebird habitat) is being drafted. The Delaware General Assembly passed a bill in 1991 enabling regulation of the horseshoe crab take and mandated monitoring. Regulations were adopted instituting a permitting system, a season, and limiting methods of collection.

The point of Cape Henlopen, DE, is currently being managed for colonial water birds, primarily under the DE Piping Plover Management Plan. Large portions of the point are closed seasonally for plovers and many other shorebird species benefit. 


Special Information 

Economic value of Delaware Bay's watershed: $10 billion!

Read the article by Sandy Bauers, Philadelphia Inquirer:
Delaware Estuary: $10 billion and counting...

View the report by University of Delaware:
Economic Value of the Delaware Estuary Watershed (pdf). 

Scientists urge Maryland to enact a moratorium on horseshoe crab harvesting.

Read the article by Candy Thomson, Baltimore Sun:
Red Knot population continues to dwindle.



Delaware Bay WHSRN Site 25th Anniversary Event a Major Success!

On May 9, 2011, partners from throughout the hemisphere gathered in Bivalve, Port Norris, NJ, to celebrate the 25th anniversary of Delaware Bay's designation as a WHSRN Site of Hemispheric Importance. This celebration highlighted the site's importance for migrating shorebirds, especially the imperiled rufa subspecies of Red Knot (Calidris canutus). Delaware Bay was also WHSRN's inaugural site, therefore the event was an opportunity to also honor the visionaries and pioneers of this hemisphere-wide shorebird conservation network.

Many thanks to everyone who made this event an enormous success!

Highlights from the Delaware Bay 25th Anniversary event

Keynote speaker Henry M. Paulson, Jr., emphasizes that a healthy environment is key to a healthy economy/ © Diego Luna Quevedo


Special letter from Charles Duncan, Executive Director, WHSRN Executive Office

The News of Cumberland County:
Delaware Bay Celebrated as a Site of Hemispheric Importance in Bivalve with Keynote Speaker Henry Paulson

The Press of Atlantic City:
Scientists using cannon-propelled nets to collect and study New Jersey shorebirds

Cumberland County News:
Delaware Bay Site of Hemispheric Importance 25-year anniversary event to be held in Bivalve




Amanda Dey
New Jersey Division of Fish and Wildlife
Endangered and Non-Game Species Program
New Jersey Division of Fish and Wildlife

Additional Resouces

Bryant, T.L. and J.R. Pennock eds. 1988. The Delaware Estuary: Rediscovering a Forgotten Resource.

Burger, J. 1983. Survey of Shorebird utilization of Delaware and Raritan Bays in relation to energy activities. Final Report, Contract 5‑G‑9(82‑29‑CEIP) to Endang. and Nongame Species Prog., NJ Dept. of Environ. Protect. 71 pp.

Burger J., L. Niles, and K. Clark. 1996. Importance of Beach Mudflat and Marsh Habitats to Migrant Shorebirds on Delaware Bay. Biological Conservation 79:283-292

Burger, J. 1997. Effects of oiling on Feeding Behavior of Sanderlings and Semipalmated Plovers in New Jersey. Condor 99:290-298.

Clark, K. 1983. Research Summary: 1986 Delaware Shorebird Project Part 2, aerial survey. Unpub. manuscript. 42 pp.

Clark, 1987. 1986 Delaware Bay Shorebird Project: Aerial Survey. Endangered and Nongame Species Program, Division of Fish, Game, and Wildlife. NJ Department of Environmental Protection. 9 pp.

Clark, K., L.J. Niles, and J. Burger. 1993. Abundance and distribution of migrant shorebirds in Delaware Bay. Condor 95:694-705